Noun: air bladder
- An air-filled sac near the spinal column in many fishes that helps maintain buoyancy
"The fish adjusted its air bladder to swim at different depths";
- swim bladder, float
- (botany) an inflated sac or bladder filled with air in some aquatic plants
"Seaweed species often have air bladders to help them float"
Derived forms: air bladders
Type of: sac
Encyclopedia: Air bladder